Compact arc discharge fluorescent lamps are known in which the envelope includes at least two longitudinally extending leg members joined together by a transversely extending envelope portion. Examples of such lamps which are commercially available are the "Twin Tube" and "Double Twin Tube" fluorescent lamps manufactured by GTE Sylvania, Danvers, Mass. Other examples are disclosed in U.S. Pat. No. 4,374,340, which issued to Bouwknegt et al. on Feb. 15, 1983; U.S. Pat. No. 4,426,602, which issued to Mollet et al. on Jan. 17, 1984; and U.S. Pat. No. 4,481,442, which issued to Albrecht et al. on Nov. 6, 1984.
In lamps of the above type, in which a plurality of spaced-apart leg members are employed, breakage of the transversely extending envelope portion may occur as the result of inward deflection of the longitudinally extending leg members caused during handling of the lamp.
In order to eliminate the chance of lamp breakage, it is known in the art to attach a separate brace member between the leg members to prevent the compression of the leg members. A "slip-on" brace member is disclosed in U.S. Pat. No. 3,337,035, which issued to Pennybacker on Aug. 22, 1967. The brace is made from stiff wire and is provided with arcuate loops at each end that are slipped over and compressively grip the legs of a U-shaped envelope. While braces of this type work satisfactorily, the looped portions of the brace may cause the brace to fit two tightly or too loosely on the lamp.
Braces which are formed to interfit with lamp base members are also known in the art. Examples of such braces are disclosed in U.S. Pat. No. 3,548,241, which issued to Rasch et al. on Dec. 15, 1970; U.S. Pat. No. 3,579,174, which issued to Gilbert, Jr. on May 18, 1971; and U.S. Pat. No. 4,217,630, which issued to Albrecht on Aug. 12, 1980. Disadvantages of all of the above braces include the added cost incurred for the additional base components.